如何旋转图像但不切割边缘IOS

Question

帮助，我是 ios 编程新手，我想旋转 UIImage 但我不希望边缘被切割或松开图像的某些部分。

这是我的代码：

double angle = M_PI * 10/ 180; CGSize s = {image.size.width, image.size.height}; UIGraphicsBeginImageContext(s); CGContextRef ctx = UIGraphicsGetCurrentContext();

CGAffineTransform transform = CGAffineTransformIdentity;
transform = CGAffineTransformTranslate(transform, image.size.width/2, image.size.height/2);

transform = CGAffineTransformRotate(transform, angle);
transform = CGAffineTransformScale(transform, 1.0, -1.0);

CGContextConcatCTM(ctx, transform);

CGContextDrawImage(ctx,CGRectMake(-[image size].width/2,-[image size].height/2,image.size.width, image.size.height),image.CGImage);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil);

图像正在旋转，但由于部分图像已被剪切，因此框架的大小没有改变。

输出：https://fbcdn-sphotos-e-a.akamaihd.net/hphotos-ak-xpf1/t1.0-9/1555286_761679470521535_1800180000235265553_n.jpg

预期输出：https://fbcdn-photos-g-a.akamaihd.net/hphotos-ak-xfa1/t1.0-0/10314770_761675840521898_6536715783383115855_a.jpg

请帮帮我，谢谢。

Answer 1

这可能就是您要搜索的内容。

只需将以下代码复制到您要在其中旋转图像的.m 文件的末尾（@end 之后）。

@interface UIImage (RotationMethods)
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees;
@end

@implementation UIImage (RotationMethods)

static CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;};

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees 
{   
    // calculate the size of the rotated view's containing box for our drawing space
    UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
    CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
    rotatedViewBox.transform = t;
    CGSize rotatedSize = rotatedViewBox.frame.size;

    // Create the bitmap context
    UIGraphicsBeginImageContext(rotatedSize);
    CGContextRef bitmap = UIGraphicsGetCurrentContext();

    // Move the origin to the middle of the image so we will rotate and scale around the center.
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

    //   // Rotate the image context
    CGContextRotateCTM(bitmap, DegreesToRadians(degrees));

    // Now, draw the rotated/scaled image into the context
    CGContextScaleCTM(bitmap, 1.0, -1.0);
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;

}

然后像下面的例子一样旋转你的图像：

CGFloat degrees = 90;
yourImage = [yourImage imageRotatedByDegrees:degrees];